Roof Rafter Measurements

Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less.

Roof rafter measurements.

Use the number boxes to enter the value in feet inches and fraction inches and fraction. It is always better to have a large rafter rather than be concerned with a sagging roof. Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. Includes result for hip valley factor slope factor and the roof slope in degrees.

Take a direct measurement of the width of the roof. Access one of the rafters then take the measurement this way. The default heel for gambrels is 1 2 of the lower rafter plumb cut height. Just snap a few photos of the exterior of the house with the hover app and our patented technology will take it from there.

Squaring building lines example our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof. Here the number is 941 86 inches. If they are not then click here for the unlevel wall rafter calculator. Once the digital property is complete you will receive detailed exterior measurements and an interactive 3d model to help homeowners design their projects.

The most precise way to find the roof s slope is by measuring it from the underside. This must be from walls that are of equal heights. Use a level against the underside of the rafter you re measuring to get the most accurate value. Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall.

Our patented technology calculates square footage and linear measurements for the roof siding windows trim and more. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Use these two tables for roof rafters with a slope greater than 3 in 12.

Locate the level s 12 inch mark. Here the number is 1166 66 inches. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch.

The above spans are based on american softwood lumber standard sizes.